Very cold H_BATT_TEMP observed via OBDII -- normal?

[WattsUp]

I recently got a wifi OBDII dongle and FORScan working using my iPhone. I've begun monitoring a few things in my FFE.

I found various battery temperature PIDs in the BECM module, one of which is named "H_BATT_TEMP" (which I believe is short for "Hybrid/EV Battery Temperature".

Over the last few days, I've observed that the reported H_BATT_TEMP value is normally in the 30's (measured in Fahrenheit). I've seen measurements like 30 F, 32 F, and most of the time 34 F. It stays pretty constant.

This seems a bit strange, why would my battery temperature be hovering around freezing? I live in the Bay Area in California and, right now, the ambient daytime temperature has been around 80 F.

From what I understand, a "normal" battery temperature for the FFE is something in the 80s and 90s, and usually the temperature regulation (cooling-wise) kicks in around 98 F. Indeed, the value reported by FORScan for the "AVERTEMP" PID is 91F, which seems more in-line with this expectation.

In my case, perhaps the sensor which provides the value for H_BATT_TEMP is defective, and reporting (false) low values? Or, perhaps the reported temperature is accurate and some other system is malfunctioning and excessively cooling the battery?

Can someone else (who has OBDII access to their FFE) let me know what you normally see for your H_BATT_TEMP value? Thanks!

 

[hybridbear]

I recently got a wifi OBDII dongle and FORScan working using my iPhone. I've begun monitoring a few things in my FFE.

I found various battery temperature PIDs in the BECM module, one of which is named "H_BATT_TEMP" (which I believe is short for "Hybrid/EV Battery Temperature".

Over the last few days, I've observed that the reported H_BATT_TEMP value is normally in the 30's (measured in Fahrenheit). I've seen measurements like 30 F, 32 F, and most of the time 34 F. It stays pretty constant.

This seems a bit strange, why would my battery temperature be close to freezing? I live in the Bay Area in California and, right now, the ambient daytime temperature has been around 80 F.

From what I understand, a "normal" battery temperature for the FFE is something in the 80s and 90s, and usually the temperature regulation kicks in around 98 F. Indeed, the value reported by FORScan for the "AVERTEMP" PID is 91F, which seems more in-line with this expectation.

In my case, perhaps the sensor which provides the value for H_BATT_TEMP is defective, and reporting (false) low values? Or, perhaps the reported temperature is accurate and some other system is malfunctioning and excessively cooling the battery?

Can someone else (who has OBDII access to their FFE) let me know what you normally see for your H_BATT_TEMP value? Thanks!

Perhaps that PID is reporting in Celsius. If you add a gauge when the default is set to C and then add other after the default is charged to F the old gauges will continue to show C. I think that's what the FORScan creators explained on their forum. Could that be what's happening? our H_BATT_TEMP always reads exactly the same as the AVERTEMP PID. Our battery has usually been in the high 70s.

 

[sefs]

All vehicle temperature parameters are reported in Celsius. Your viewer must do the conversion to Fahrenheit.

 

[jmueller065]

I think that's what the FORScan creators explained on their forum. Could that be what's happening?

Yes that is exactly what the FORScan developers said: Any items you've added to the dashboard before switching to F will show C.

 

[WattsUp]

I think that's what the FORScan creators explained on their forum. Could that be what's happening?

Yes that is exactly what the FORScan developers said: Any items you've added to the dashboard before switching to F will show C.

The FORScan iPhone app doesn't seem to have a "default" setting for F or C (or at least I haven't found it). I can only go into the configuration for each gauge is set it to individually to F or C.

In any case, my gauge for H_BATT_TEMP is definitely set to F (see image in my next post). I also tried deleting the gauge and re-adding it.

 

[WattsUp]

All vehicle temperature parameters are reported in Celsius. Your viewer must do the conversion to Fahrenheit.

And I do have my viewer set to F...



Note that the MINTEMPBECM reading also seems to reflect the 30 F shown for H_BATT_TEMP, which lends some credence to the measurement actually being 30 F (if both PIDs are reflecting the same data point).

Definitely seems strange, eh?

 

[WattsUp]

Today, after a multi-hour charge at Level 1, FORScan showed even lower numbers for H_BATT_TEMP and MINTEMPBECM.

I saw 20, 21, and 23!

Also, the H_BATT_TEMP and MINTEMPBECM readings were bobbing between 21 and 23 for a while as a drove home, with MINTEMPBECM matching the H_BATT_TEMP about a second after each change.

 

[hybridbear]

Today, after a multi-hour charge at Level 1, FORScan showed even lower numbers for H_BATT_TEMP and MINTEMPBECM.

I saw 20, 21, and 23!

Also, the H_BATT_TEMP and MINTEMPBECM readings were bobbing between 21 and 23 for a while as a drove home, with MINTEMPBECM matching the H_BATT_TEMP about a second after each change.

Have you tried clearing all the gauges & adding them again to see if it's a F/C issue? 21 C (~70 F) sounds pretty reasonable for a minimum cell temp.